The Galaxy Federation learns that ORN houses Plealos deep below Nebula's surface when not in use and takes the opportunity to plan an operation to take it down. They send the next iteration of their Fire LEO series of fighter craft, the Fire LEO-02 "Exceliza", to destroy ORN bases on Nepura and eventually find and destroy Plealos. The player controls the Exceliza and travels through a variety of stages to accomplish this goal.

The Fire LEO-03 "Styx" was created as a craft small enough to avoid detection by Cerberus, but equipped with the firepower of a large starfighter. It was deployed on a mission to destroy the five cloaking devices installed by the ORN Empire in five different planets, infiltrate the Empire's headquarters, and destroy its emperor, the bio-computer "Khaos".

This mass production variant of the Styx made a short appearance in Thunder Force IV. During the Volbados pursuit in stage 5, a squadron of Styx is sent to support the Fire LEO-04 "Rynex", two of which help circumnavigate the cruiser while another six assist in the battle against the ORN Faust. However, they're no match for ORN Faust, which destroys all of the Styx squadron, except for three ships which appear later to send the new Thunder Claw and install it on Rynex.

Styx Rev.2 is to be an identical copy of the original Fire LEO-03 "Styx", and the second "Mass Production" version of the Fire LEO-03 it was the second ship in the game to feature an RVR-like blue and white colorscheme with a green cockpit, which like the Fire LEO-05P "Syrinx" will makes us think again on an Earth Side-Galaxy Federation collaboration on its development. It's total crew is unknown, but it was highly probable that the ship was double seated like the original Styx.

Although the ship was cancelled along with the game, the concept of a mass produced variant was re-taken and used on the Fire LEO-04C "Rynex-R" in Thunder Force VI.

With an initial defeat, the Galaxy Federation develop this small and powerful craft to fight back the forces of Vios. Right after the accomplishment of the mission, the Vios fortress massive explosion heavily damaged the ship, but didn't destroyed it, leaving it drifting through space until it reached the Oort cloud, where it was discovered by the EASA Space Probe "Sekika 3", the humans know this discovery as the "Vastian's Steel" or "Vasteel", its discovery triggered an evolution in Earth's technology known as "Vasteel Technology", but also unleashed a war against the human race. Rynex was destroyed by the RVR-02 "Vambrace" during a battle against the Sword Fleet.

Sprite of Rynex

The Rynex pilots were Roy S. Mercury and Carol T. Mars, it is unknown who piloted it when it was rebuilt as Vasteel Original, it could be controlled by the Guardian, but there's no clues about that. When it was revived in Thunder Force VI, the Galaxy Federation researchers created a mass-production variant known as Rynex-R.

It is also the only Fire LEO which used an Extra Weapon Bay, an Earth-made, Guardian created variant of the RVR Brigandine equipment.

Rynex is also considered to be the series' mascot, as it tends to be the most recognizable craft in the series as well as appearing in a majority of the installments, this ship could be the "Flag" model of the Federation forces.

Also known as "Rynex 改" (Rynex Kai), The Rynex-R is the result ofGalaxy Federation researchers who managed to take advantage of the original Rynex's design and successfully mass-produced the craft in large quantities. The ship needs specific amount of skill to pilot it. The Thunder Sword add-on is now implemented from the start, though it is inferior to the destructive power employed by the original. However the ship makes up for this by strengthening diversion of each armaments.

Due to the cancellation of Thunder Force VI on the Sega Dreamcast we can only speculate about this ship. Unlike the traditional red colors of the Fire LEO series, Syrinx featured an RVR like blue color scheme, which will make us think of a possible Earth-Galaxy Federation joint project. This ship can fold its wings for shift from Attack Mode to Speed Mode.

Due to the cancellation of the game, the identity of its pilot is a mystery.

Despite its cancellation, the ship design was retaken from its forgotten origins, redesigned and used on the PS2 game Thunder Force VI, where it saws the light as an RVR-ORN Faust hybrid.

This is the newest Fire LEO unit developed by the 13 Constellations ARKS Force to do battle against Mephist, and it has the same attack power than the RVR-03G1 "Bracer". Unlike the RVR, it can't fire an Over Weapon since overweapon wasn't installed on Syrex